NASA mission calculates global ice melt and rising sea levels

From 2003 to 2010, NASA satellites systematically measured all of
Earth's melting glacial ice--the results added up to 4.3 trillion tons
of water and a global sea level rise of half an inch.
Put in perspective, that's enough ice to bury the entire U.S. 1.5-feet deep.
These calculations are detailed in a new study released today by a team of scientists at the University of Colorado. The scientists used satellite measurements from the NASA Gravity Recovery and Climate Experiment (GRACE), which launched in 2002 and focused on how melting ice from glaciers and ice caps is adding to global sea level rise.
"Earth is losing a huge amount of ice to the ocean annually," said
professor John Wahr, who helped lead the study. "These new results will
help us answer important questions in terms of both sea rise and how the
planet's cold regions are responding to global change."
Of all
of the ice loss measured yearly, around one quarter came from glaciers
and ice caps outside of Greenland and Antarctica, which equaled about
148 billion tons or 39 cubic miles, according to the study. Melting ice
from Greenland, Antarctica, and nearby caps and glaciers averaged
roughly 385 billion tons, or 100 cubic miles, per year.
This
study is groundbreaking because it is the first time that all of the
nearly 200,000 glaciers worldwide have been monitored together for an
extended amount of time. Typically, estimates have been made on just a
few glaciers and then the results are applied to other glaciers that
have not yet been monitored.

Some of the study's results are unexpected, such as the ice melt
in Asia's Himalayan, Pamir, and Tien Shan mountain ranges. Previously
estimates were as high as 50 billion tons of ice loss a year in the
three ranges combined, but calculations from GRACE put it closer to 4
billion tons annually. "The GRACE results in this region
really were a surprise," Wahr said. "One possible explanation is that
previous estimates were based on measurements taken primarily from some
of the lower, more accessible glaciers in Asia and extrapolated to infer
the behavior of higher glaciers."
Although some of the findings
in this study are lower than prior estimates, NASA warns that melting
glacial ice and sea level rise are still a deep concern regarding
climate change.
"This study finds that the world's small glaciers
and ice caps in places like Alaska, South America, and the Himalayas
contribute about .02 inches per year to sea level rise," said NASA
scientist Tom Wagner. "While this is lower than previous estimates, it
confirms that ice is being lost from around the globe, with just a few
areas in precarious balance. The results sharpen our view of land ice
melting, which poses the biggest, most threatening factor in future sea
level rise."
Watch this animated video from the GRACE mission,
which shows recent trends in ice mass changes in the world's mountain
glaciers and ice caps.